JPH0934473A - Silencing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the occupying space, suppress the power consumption of a sonic wave generating means, and reduce the device cost by locating the sonic wave generating means in the backmost part in a labyrinth whose outlet is opening, and arranging the labyrinth so that its acoustic path length is such as to generate resonance with the chief frequency component of the silencing sonic wave emitted by the sonic wave generating means. SOLUTION: The main rectangular part of a casing 2 consisting of two rectangles has a minor depth, and therein an acoustic path 10 in the form of a labyrinth is formed by bulkheads 3-6 extending up and down and another bulkhead 7 extending in the horizontal direction. In the backmost part in this labyrinth a speaker 8 as sonic wave generating means is installed, and its front faces the labyrinth 10, while the back part confronts a closed space in a projection formed in a single piece in a part under the easing 2. The labyrinth 10 constitutes acoustic path, whose length L, i.e., distance along the labyrinth 10 from the speaker 8 to opening 2C, is designed so as to generate resonance with the chief frequency component of the silencing sonic wave generated by the speaker 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer.

[0002]

2. Description of the Related Art The applicant of the present application has previously disclosed in Japanese Patent Laid-Open No. 7-104771 that, for example, when a noise source is a vibration application device, the noise should not be transmitted to neighboring people. We have developed a silencer. However, when the noise from the noise source is large, as a matter of course, the level of the silencing sound wave for silencing the noise must also be high. However, in the conventional silencer, the size of the device must be increased, and the power supplied to the sound wave generating means is also large, which increases the cost of the device.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a silencer capable of reducing power consumption, slimming or downsizing the entire device, and reducing device cost. The purpose is to

[0004]

According to the invention of claim 1, the above object is to provide a casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, and a noise source. Noise detecting means for detecting the noise of, and at least a detection signal of the detecting means is formed to form a sound deadening sound wave signal for reversing the density of the noise generated by the noise source. In a muffling device having one or more muffling units provided with a muffling signal generating device for supplying to the sound wave generating means, the main part of the casing being deep in the muffling device arranged near or around the noise source. Shows a small rectangular parallelepiped shape, the inside of which forms a labyrinth so as to obtain a sufficiently long sound path length by a plurality of partition walls, the sound wave generating means is disposed at the deepest part of the labyrinth, and the exit of the labyrinth is the At the opening The sound path length of the maze is such that the main frequency component of the silencing sound wave generated from the sound wave generating means resonates, and the back part of the sound wave generating means is a protrusion integrally formed in the lower part of the part. This is achieved by a sound deadening device, characterized in that it faces inside.

Further, according to the invention of claim 2, the above object is to detect the noise of a casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, and a noise source. And a noise detection means for receiving at least the detection signal of the detection means to form a silencing sound wave signal for reversing the density of the noise generated by the noise source, and supply the silencing sound wave signal to the sound wave generating means. In the muffling device in which one or a plurality of muffling units including the muffling signal generating device are arranged in proximity to or around the noise source, the casing has a rectangular parallelepiped shape with a small depth. By the partition wall whose cross-sectional shape is a closed loop,
Forming a pair of symmetrical sound paths on both sides thereof, the sound wave generating means is attached to the center of the bottom wall portion of the partition wall, and the back portion thereof faces the closed space formed by the closed loop,
The length of the pair of sound paths is achieved by a silencer characterized in that a main frequency component of a silencing sound wave generated by the sound wave generating means resonates.

Further, according to the invention of claim 5, the above object is to detect the noise of a casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, and a noise source. And a noise detection means for receiving at least the detection signal of the detection means to form a silencing sound wave signal for reversing the density of the noise generated by the noise source, and supply the silencing sound wave signal to the sound wave generating means. In a muffler having one or a plurality of muffling units provided with a muffling signal generating device, the main part of the casing having a rectangular parallelepiped shape with a small depth. A maze is formed by a plurality of partition walls so as to obtain two sufficiently long sound path lengths, and the sound wave generating means is composed of two sound wave generators, each of which is disposed at the innermost portion of the maze. Said opening comprises two openings,
The outlets of the mazes are the openings, the sound path lengths of the mazes are different, and the lengths of the silencing sound waves generated from the sound wave generators are such that different main frequency components resonate with each other. The silencer is characterized in that the back of the generator faces into a projection integrally formed in the lower part of said part.

[0007]

According to the first aspect of the invention, the depth is small and the shape is a rectangular parallelepiped. However, since it is smaller than the conventional one as a whole and a sufficiently long sound path length is formed inside, it is generated from the sound wave generating means. Even if the wavelength of the sound-deadening sound wave to be generated is long, that is, even if it is a low frequency, it is possible to obtain a length that resonates with the sound-absorbing sound wave. A sound-deadening sound wave can be generated, and its distortion is small, so that a large noise from a noise source can be effectively silenced. Reduces power consumption, muffles loud noise, and
The casing can be downsized, and the device cost can be greatly reduced.

According to the invention of claim 2, while achieving the effect of claim 1, the back surface of the sound wave generating means is further formed in the rectangular casing by the partition wall having a closed loop cross-sectional shape. By facing the space, it has a sufficiently large volume, so that in addition to the resonance action in the sound path, it is possible to smooth the vibration of the sound path generating part, further reducing power consumption. While making the device small, the entire device can be made smaller, and the device cost can be greatly reduced.

According to the invention of claim 5, while exhibiting the action and effect of the above invention, it is possible to further resonate with different frequency components in the pair of sound path lengths, and also in the frequency components in the band between these frequencies. Even if the noise source resonates and the frequency component of the noise source covers a wide range, the noise component can be sufficiently silenced. Therefore, the power consumption supplied to the sound wave generating means can be reduced and the device cost can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a silencer according to a first embodiment of the present invention, which is designated by 1 as a whole, and a main rectangular parallelepiped portion 2a of a casing 2 having two rectangular parallelepipeds has a depth (see FIG. 2). The width of the left and right sides of the partition walls is small, and as shown in FIG.
A maze-like sound path 10 is formed by the partitions 5 and 6 and the partition wall 7 extending in the horizontal direction. A speaker 8 as a sound wave generating means is disposed at the innermost part of the maze, and the front part thereof faces the maze 10 , but the rear part thereof is the casing 2.
Space inside the protrusion 2b formed integrally with the lower part of the
Facing the 9 . Further, the maze 10 serves as a sound path, and the sound path length L, that is, the distance from the speaker 8 to the opening 2c along the maze 10 resonates with the main frequency component of the silencing sound wave generated by the speaker 8. Is the length. That is, as is well known, the sound path length is an integer multiple depending on the order, but since the sound path length is inversely proportional to the resonance frequency, the lower the frequency, the larger the sound path length must be. Although the speaker 8 generates a sound-deadening sound wave having a frequency component whose main component is the same as the frequency, the speaker 8 has such a length as to resonate with the sound wave. An opening 2c is formed in one side wall portion of the casing 2, that is, a side wall portion on the side opposite to the noise source, as shown in the drawing, and a muffling deviation detection microphone 11 is arranged facing the front surface. This detection output is supplied to the silence signal generator 12 shown in FIG. A noise detection microphone 13 is attached to the other side wall of the casing 2 so as to detect noise from a noise source, and this is covered with a film 13a made of a thin and low-density material. Does not directly touch the main body of the microphone 13. The detection output from the microphone body 13 is supplied to the muffling signal generator 12 via the lead wire t. In FIG. 2, there are noise sources such as factories and airports on the left side, but the noise from this is divided into directions toward A, B, and C. Since the direction toward A is outdoors, it is toward the sky and noise in the B direction. Is propagated to the right side of the casing 2 in the figure over the casing 2 of the silencer 1. Further, the C component propagating in the horizontal direction collides with the left side wall portion of the casing 2, and due to the configuration of the casing 2 having a hollow rectangular parallelepiped shape, it is equivalent to a double sound insulation wall for C, and this is sufficient. Attenuated C '
Is a propagation component that is hardly transmitted to the right of the right side wall.

Next, referring to FIG. 13, a silence signal generator 1
2 will be described in detail. The analog output of the noise detector 13 is amplified by the amplifier 136 and supplied to the A / D converter 137, where the analog value is converted into a digital value, and the result is supplied to the adaptive algorithm 139 and the adaptive filter 140. Supplied. The adaptive algorithm 139 changes the constant and the transfer function of the adaptive filter 140 according to parameters that change with time in an actual noise environment, such as atmospheric pressure, temperature, humidity, sound pressure and frequency components. As a result, a sound wave signal is generated such that a sound wave having the same level as the sound wave as the noise detected at the position of the microphone 11 but having the opposite density is obtained at the position of the microphone 11. In the D / A converter 142, the digital input is converted into an analog force output, which is the amplifier 1
The signal is amplified by 43 and supplied to the speaker 8. As a result, in FIG. 2, the sound wave B transmitted from the noise source on the left side (not shown) can be made substantially zero at the position of the muffling deviation detection microphone 11, but the analog output detected by the microphone 11 is increased. The signal is amplified by the device 145, converted into a digital value by the A / D converter 144, and supplied to the above-described adaptive algorithm 139, where a predetermined calculation is performed. That is, if the sound wave is not zero at the position of the muffling deviation microphone 11 as the error sensor, this is corrected. The silencer 1 according to the first embodiment of the present invention is configured as described above, and its operation will be described below.

In FIG. 2, noise generated from an airfield (not shown) propagates in the directions indicated by A, B, and C. Of these, the sound wave component indicated by B propagates to the human ear. is there. As shown by the alternate long and short dash line, the speaker 8 in the casing 2 receives a muffling signal calculated by the muffling signal generator 12 upward, and this diaphragm is driven to pass through the sound path 10 to muffle sound waves. Is propagated and the opening 2c
2 propagates to the right in FIG. 2 and reaches the deviation detection microphone 11, but the noise detected by the noise detection microphone 13 is amplified by the amplifier 136 in FIG. The signal is converted into a digital signal by 137 and supplied to the adaptive algorithm 139 and the adaptive filter 140. As a result, noise from the noise source interferes at the position of the muffling deviation detection microphone 11 to form a muffling signal that cancels the noise, and this is converted by the D / A converter 142 into an analog value, which is then amplified by the amplifier 143. It is amplified and supplied to the speaker 3. The silenced sound wave is propagated upward from the speaker 3 along the sound path 10 as indicated by the alternate long and short dash line, and propagates outward through the opening 2c. The muffling deviation detection microphone 11 detects the muffling deviation due to the interference between the noise sound wave and the muffling sound wave, and this is supplied to the muffling signal generator 12, and the difference is converged to zero by the adaptive algorithm 139 and the adaptive filter 140. Controlled to be done. Therefore, as a result, the sound deadening sound wave B is almost completely muted at the position of the sound deadening deviation detection microphone 11, and the noise component B is hardly propagated on the right side of the drawing. Therefore, the noise component B from the noise source is hardly transmitted to the human ear located on the right side in the figure. Further, in order to block the noise component B, a high soundproof wall was conventionally required, but the same effect can be obtained at a much lower height.

In the muffling signal generator 12, the microphone 13 detects noise having a correlation with the noise of the airfield, and the noise is supplied to the muffling signal generator 12. Further, the airfield noise is mainly aircraft engine noise, which has a certain frequency component, and is preferentially supplied from the muffling signal generator 12 to the speaker 8 as a muffling signal.

The muffling signal from the speaker 8 propagates along the sound path 10 toward the opening 2c and propagates through the maze 10. This length is the frequency component mainly of the engine sound of the airplane at the airfield. Since the sound-deadening sound wave whose main component is this frequency component propagates along the maze 10 , the maze 1
The sound deadening sound wave that resonates within 0 goes from the opening 2c to the front sound deadening deviation detection microphone 11 . Note that the mute deviation detection microphone 1
Since 1 is horizontally opposed to the opening 2c,
Further, when the noise of the B component propagating to the right over the casing 2 reaches the muffling deviation detection microphone 11, the noise propagating to this position is silenced. Further, a mute deviation is detected by the microphone 11, and this is the mute signal generator 12
Is supplied to. The above-described mute signal is generated according to the design principle of the adaptive algorithm 139 provided in the muffling signal generation device 12, but the mute signal is received by the mute deviation detection microphone 11 and converges so that the deviation becomes zero. Therefore, the noise propagated to the right (private house) in the figure is almost zero.

According to this embodiment, the speaker 8 is installed in the sound path 10.
By resonating the main frequency component of the sound-deadening sound wave from the, the power consumption can be minimized for a constant noise level, and the distortion of the sound wave can be reduced. Therefore, the size of the entire device for silencing a certain noise can be made much smaller than the conventional one, and according to the present embodiment, the rectangular portion occupying the main part of the casing 2 is slim, that is, Since the shape has a small depth,
It looks good and occupies a small space, and its production cost can be greatly reduced.

The protruding portion 2b is formed integrally with such a slim rectangular parallelepiped portion with a minimum size.
By making the rear part of the speaker 8 face this,
The speaker 8 can freely vibrate its sound wave generating portion without receiving a large resistance, and further reduce power consumption in combination with the above-described resonance effect to achieve an effective sound deadening effect. Since the protruding portion 9 for performing the vibration without resistance of the sound wave generating portion is formed in contact with the ground below the slim rectangular parallelepiped portion, it does not interfere with the surroundings.
Further, it is possible to form the minimum necessary closed space that facilitates the vibration of the back surface portion.

3 and 4 show a muffler according to a second embodiment of the present invention, which is designated by 21 in its entirety, but the casing 22 having a rectangular parallelepiped shape has a small depth and is slim as in the first embodiment. The shape. As shown in FIG. 3, the inside is a partition wall 23 showing the cross-sectional shape of a convex closed loop.
Thus, a pair of sound paths 29a and 29b are defined on both sides thereof. The second wall extending horizontally on the upper wall surface of the partition wall 23
Partition walls 24a and 24b are formed, and throat openings 25a and 25b are formed inward of the partition walls 24a and 24b. In addition, a pair of laterally elongated slit-shaped openings 22 a, 22 are located between the partition walls 24 a, 24 b and the upper wall portion of the casing 22.
b is formed. These are the throat 25a,
The pair of sound paths 29a and 29b communicate with each other via 25b.

A circular hole is formed in the bottom wall surface of the partition wall 23 having a closed loop cross section, and the speaker 28 is fixed to the circular hole. Therefore, the back surface faces the closed space 27 formed in the partition wall 23, and the front surface faces the sound path portion 30 extending in the horizontal direction. It communicates with 29a and 29b. In addition,
Although not shown, a muffling deviation detection microphone is provided facing the front of the openings 22a and 22b, and the output thereof is also supplied to the muffling signal generator 12 (not shown). A noise deviation detection microphone 13 is fixed to a side wall portion of the casing 22 facing the noise source side, and its output is supplied to the muffling signal generation device 12.

The silencer 21 according to the second embodiment of the present invention is constructed as described above, and its operation will be described below.

Also in this embodiment, the lengths L1 and L2 (L1 = L2) resonating with the main frequency component of the noise source.
Through the sound paths 29a and 29b
Propagates the sound-deadening sound waves generated by the throat openings 25a, 25b.
Propagate horizontally outward through b. Sound path 29a,
Since the main frequency component resonates with 29b,
Opening 22 provides the required level of sound-deadening sound waves with the lowest power consumption.
In addition, according to the present embodiment, since the horizontal partition walls 24a, 24b are provided with the pair of slit-shaped throats 25a, 25b, the sound path 29a is transmitted. , 29b, the phase of the sound wave propagating through can be transmitted almost identically in any part of the opening while having a long opening.
Phase-matched silence sound waves can be emitted outward through the openings 22a and 22b. Further, according to this embodiment, the closed space 27 for smoothing the vibration of the sound wave generating portion of the speaker 28 is formed as a portion protruding outward from the main rectangular parallelepiped portion as in the first embodiment. However, since it is formed inside the casing 22 having a rectangular parallelepiped shape, the occupied space can be made smaller by making the shape slimmer than in the first embodiment.

As described above, the power consumption can be minimized in order to obtain a constant level of the sound wave for silencing the noise, and the space volume occupied by the sound deadening device can be further reduced. . Furthermore, according to the present embodiment, since the slit-shaped openings 22a and 22b are formed in the side wall portions, raindrops do not invade, and even if they do, the common part 30 of the sound path is not exposed. Since the speaker 28 is arranged downward, raindrops do not collect on it. Therefore, the weather resistance can be made excellent.

5 and 6 show a silencer according to a third embodiment of the present invention, which is designated by 41 in its entirety. This casing 42 is composed of two rectangular parallelepiped parts, and the main rectangular parallelepiped part 42a has a small depth and a slim shape, and inside thereof, as shown in FIG. The partition wall 43 substantially defines two spaces, which are formed by a pair of second partition walls 43a, 43b extending in the vertical direction and a pair of third partition walls 44a, 44b extending vertically inside the casing 4.
A pair of sound paths 50a , 50b formed with a maze inside 2
Is defined. A pair of speakers 48a,
48b is provided, and the other rectangular parallelepiped portion 42b is formed as a projecting portion so as to face the back surface portion as shown in FIG. 6, but this inner space is a closed space 49, and a speaker is formed in this space. The back surfaces of 48a and 48b face. The sound paths 50a and 50b are formed as mazes, but the pair of openings 51a and 51b formed on the upper end side of the side wall of the casing 42 serve as outlets.

Further, according to this embodiment, one sound path 50b is provided.
A fourth partition wall 45 is integrally provided so as to face the intermediate portion of the. As a result, the closed space 46 is formed below the sound path 50b , but the length of the sound path 50b is shorter than that of the other sound path 50a. That is, the sound path length L4 is shorter than the sound path length L3. Although the speaker 48a, 48b is supplied with a drive signal from the muffling signal generator as in the above-mentioned embodiment even though it is not shown, the noise source is not mainly a single frequency but a frequency component having a constant bandwidth. And the sound-deadening sound waves including these components are generated by the speakers 48a, 48a.
Although generated from b, the sound path length L3 is a length that resonates with the lower limit frequency of the noise band, and the second sound path length L4 is a length that resonates with the upper limit frequency of the noise band.

The third embodiment is constructed as described above,
The operation is almost the same as in the above embodiment. According to this embodiment, two sound paths are formed, and their lengths L3 and L4 are different and resonate with two frequency components. Therefore, as shown in FIG. 8, they resonate at frequencies f1 and f2, respectively,
The output-sound pressure level at this resonance point is combined and has a peak between the frequencies f1 and f2, rather than having a peak only at two frequency components. Therefore, the synthetic silencing sound waves propagating from the openings 51a and 51b can efficiently and efficiently muffle frequency components from a wide range of noise sources included between the frequencies f1 and f2.

The other operations and effects are the same as those in the above-mentioned embodiment and will not be described.

9 and 10 show an example of the arrangement of the above-mentioned silencer. In FIG. 9, the noise source is a factory, an airport, etc. It is arranged so as to be connected. As a result, as is clear from the above, noise from factories and airports is not transmitted to private houses. Further, as described above, according to the muffling device of the present invention, since the device has a slim shape, when these are connected to each other, the effect can be further strengthened, and the aesthetic appearance is better than in the past. To improve.

FIG. 10 shows another example of the arrangement. The above-mentioned silencer 1 is embedded in both side walls of an elevated railway, road or the like, and slits formed in these side walls are used. The above-mentioned opening or opening faces outward.
According to this arrangement example, since the silencer is not visible from the outside, the aesthetics of the railway and road can be maintained as it is.

FIGS. 11 and 12 show a silencer according to the fourth embodiment of the present invention, which is designated by 60 in its entirety and is formed by connecting a plurality of silencer units 61A, 61B. However, each unit 61A, 61B ...
.. have the same configuration, so that one unit 61A will be described, this casing 68 also comprises two rectangular parallelepiped portions, and the main rectangular parallelepiped portion 68a has a slim shape as in the first embodiment. Although a sound path 69 having a length that resonates with a sound deadening sound wave generated from the speaker 66 is formed inward, according to the present embodiment, the opening 6 is formed.
The reference numeral 2 is formed not on the side wall portion but on the upper wall portion, and has a laterally long slit shape as in the second embodiment. In addition, the closed space 65 facing the back of the speaker 66 is closed in the second rectangular shaped portion 68b, so that the slim shape of the unit 61A is not impaired.

Further, according to this embodiment, the casing 61
One side wall portion 67 of A is open, and as shown by the arrow, when connecting another silencing unit 61B to this, this side wall portion is aligned and brought into contact. Then, as clearly shown in FIG. 14, a groove 64a that is formed at both ends of the side wall of the casing 68 and extends in the vertical direction,
Band-shaped coupling members 65a, 6 made of plastic on 64b
The units 61A and 61B are integrated by fitting 5b as shown in the figure. However, by such a coupling, the units 61A and 61B are temporarily connected to each other.
As shown in FIG. 1, after they are arranged vertically and horizontally in series, they are maintained in an orderly posture without breaking the arrangement posture, and the aesthetic appearance is not impaired thereafter. Further, according to the present embodiment, by opening one side wall portion of the casing 68,
Material costs can be reduced. In particular, as shown in FIG. 11, the effect is great when a large number of units are arranged.

Further, although the details of the muffling deviation detecting microphone 11 have not been described in the above embodiments, they are configured as shown in FIG. That is, the microphone 11 of this embodiment is provided with a directional microphone body 11a, which is covered with a capsule 11b made of a thin material having a low density so as to seal the microphone body 11a. It is supplied to the muffling signal generator 12 via the lead wire 11c. Since the left and right ends of the capsule 11b are rounded, turbulence does not occur here even when the wind hits, and therefore, the directional microphone body 11 ensures that the muffling deviation at this position is less disturbed and accurate. Can be detected. Of course, since the capsule 11b does not directly hit raindrops, the life of the capsule 11b can be extended.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications can be made based on the technical idea of the present invention.

For example, in the second and third embodiments described above,
Although the throat is provided near the opening to match the phase of the silencing sound waves propagating in the sound path, this may be omitted.

Further, in each of the above-mentioned embodiments, a small opening is provided in the side wall portion near the bottom wall portion of the casing, and when water is accumulated inside, it is usually plugged and periodically. You may make it discharge | emit outside by pulling out this. In this case, it is desirable that the bottom wall surface be inclined downward toward this opening.

Further, an inspection window that can be freely opened and closed may be provided so that the inside can be inspected periodically. For example, when a pigeon invades to form a nest, the sound deadening characteristics are impaired, and therefore the pigeon may be removed from this window.

For example, in the above embodiment, all the openings 2c, 25a, 25b, 51a, 5 except the fourth embodiment are
Although 1b is provided on the upper end side of one side wall of the casings 2, 22, 42, it may be provided on the upper wall when the muffling unit is placed indoors. In this case, raindrops are likely to enter from above, but since the speaker is in the maze, it is not directly hit, and it can be said that it has better weather resistance than the conventional silencer. The casing 200 may have the shape shown in FIG. 14, and the opening 200a may be formed in the wall portion that faces obliquely upward. The sound path 201 is formed as shown by the alternate long and short dash line. In any case, it is desirable that the opening be formed in a horizontally long slit shape. In any case, the opening may be formed in the upper wall portion, the side wall portion, or the inclined portion depending on the situation or environment in which the muffling unit is installed.

[0037]

As described above, according to the muffler of the present invention, it has a slim shape and the volume of the occupied space is small,
Further, the power consumption supplied to the sound wave generating means can be minimized, and the running cost and the apparatus cost can be drastically reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a silencer according to a first embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a sectional view of a silencer according to a second embodiment of the present invention.

FIG. 4 is a partially cutaway side view of the same.

FIG. 5 is a sectional view of a silencer according to a third embodiment of the present invention.

FIG. 6 is a side view of the same.

FIG. 7 is an enlarged cross-sectional view showing the structure of a muffling deviation detection microphone applied to each device of the above-described embodiment.

FIG. 8 is a frequency-output sound pressure level chart showing the operation of the third embodiment of the present invention.

FIG. 9 is a plan view showing an arrangement example of the silencer according to the first embodiment of the present invention.

FIG. 10 is a cutaway perspective view showing another arrangement example.

FIG. 11 is a partially cutaway perspective view of a silencer according to a fourth embodiment of the present invention.

FIG. 12 is a partial cross-sectional plan view of the same.

FIG. 13 is a block diagram of a silence signal generation device applied to each embodiment.

FIG. 14 is a partial cross-sectional view showing a modified example of the casing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 silencer 2 casing 3 speaker 5 silencer signal generator 8 speaker 11 silencer deviation detection microphone 12 silencer signal generator 13 noise detection microphone 21 silencer 22 casing 28 speaker 41 silencer 42 casing 48a speaker 48b speaker 60 silencer 68 casing

Claims (5)

[Claims] 1. A casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, a noise detecting means for detecting noise of a noise source, and a detection signal of at least the detecting means. In response to the noise generated by the noise source, a silencer sound wave signal for inverting the density is formed, and a silencer signal generator for supplying the silencer sound wave signal to the sound wave generating means is provided. In a muffler arranged near or around the noise source, the main part of the casing has a rectangular parallelepiped shape with a small depth, and the inside thereof is sufficiently long with a plurality of partition walls. To form a maze, the sound wave generating means is disposed at the deepest part of the maze, the outlet of the maze is the opening, and the sound path length of the maze is the muffling sound generated from the sound wave generating means. A silencer having a length such that a main frequency component of a sound wave resonates, and a back portion of the sound wave generating means faces a projecting portion integrally formed in a lower portion of the portion. 2. A casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, a noise detecting means for detecting noise of a noise source, and a detection signal of at least the detecting means. In response to the noise generated by the noise source, a silencer sound wave signal for inverting the density is formed, and a silencer signal generator for supplying the silencer sound wave signal to the sound wave generating means is provided. , Or a plurality of, in a muffler arranged near or around the noise source, the casing has a rectangular parallelepiped shape with a small depth, and the inside thereof is formed by partition walls having a closed loop cross section on both sides thereof. Forming a pair of symmetrical sound paths, the sound wave generating means is attached to the center of the bottom wall portion of the partition wall, the back portion thereof faces the closed space formed by the closed loop, The sound deadening device is characterized in that the length of the sound path is such that the main frequency component of the sound deadening sound wave generated by the sound wave generating means resonates. 3. A casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, a noise detecting means for detecting noise of a noise source, and a detection signal of at least the detecting means. In response to the noise generated by the noise source, a silencer sound wave signal for inverting the density is formed, and a silencer signal generator for supplying the silencer sound wave signal to the sound wave generating means is provided. Or a plurality of mufflers arranged near or around the noise source, wherein the opening comprises a pair of openings, and a second partition wall extending in parallel with and in the vicinity in the horizontal direction. 3. The sound deadening according to claim 2, wherein the pair of sound paths are integrally provided in the casing, a pair of slits are formed in the second partition wall, and the pair of sound paths are communicated with the pair of openings through the slits. apparatus. 4. A casing having an opening and containing a sound wave generating means for generating a silencing sound wave from the opening, a noise detecting means for detecting noise of a noise source, and a detection signal of at least the detecting means. In response to the noise generated by the noise source, a silencer sound wave signal for inverting the density is formed, and a silencer signal generator for supplying the silencer sound wave signal to the sound wave generating means is provided. In a muffler arranged near or around the noise source, the main part of the casing has a rectangular parallelepiped shape with a small depth, and the inside of the muffler has two sufficiently long walls. A maze is formed so as to obtain a sound path length, the sound wave generating means is composed of two sound wave generators, each of which is disposed at the innermost portion of the maze, and the opening is composed of two opening parts. The outlets are the openings,
The sound path lengths of the mazes are different, and the lengths are such that different main frequency components of silencing sound waves generated from the sound wave generators resonate with each other, and the back part of the sound wave generators is integrated with the lower part of the part. A silencer characterized by facing the inside of a protrusion formed in a static manner. 5. The opening is formed in a side wall portion of the casing opposite to the noise source or an upper wall portion of the casing, depending on the surrounding conditions of the installation.
The silencer according to any one of to 4.